I did it last night... i think i actually screamed...
ilvl 484 and close to 100 wipes. Had to use a purification potion otherwise i'd never make that enrage timer.
I lost my pitlord at 3%due to it tanking loads of imps, 2 doomlords and Kan. Popped everything i had and pulled it off with i think 10% hp left.
Never again...

Finally got it down , after 6 hours of wiping .
485 ilvl destruction warlock , Soulflare on Kazzak EU if you wanna check out the armory ..
The best tip I can give , is just to do it over and over til you know the mechanics of the fight and to not panic ! The reason I wiped most of the times was because I paniced when the felpuppies spawned and disabled my enslaved demon ! Or when I got the boss really low ( 20% - ish ) I started ignoring the adds , don't do it !
My priority was something along the lines of : Dodging chaos bolts > interupting the cataclysm >Keeping my Enslave > killing Fel puppies > Banish doom lord > Dispelling the dots off me > killing imps > dpsing the boss

o i love this fight , ive done it 5 times so far!!!
It's hilarious at the end
i missed some of those sneaky Fel Imps back there , when 2nd wave of felpuppies come boss was already feeling the pain out of those Shadowburns , Pit Lord lost , Doomguard un Banished , 3 felpuppies and some Fel imps at the back... but yet had to die!
I did this to help a guy from US realm in 489 ilvl gear.

I must be the worst warlock ever, can't get past the second felhunter wave even if my life depended on it.

How are you handling it? This phase was what wiped me the most, but it was usually because I was worrying about too much. If you banish the doomguard right as he starts casting and use pit lord breath on yourself you have nothing to worry about other than the felhunters, which is the same as the first wave and shouldn't ruin your mojo.

i have the same issue, for the most part i get to the 2 nd felhunter phase every attempt with the oddball ones that i dont make it, i handle it just the same as the first, los pit lord, ROF portal, go to the pillar to the left and havoc one, i may however not be pooling enough embers to kill them fast enough, some how though they still get the enslave dispelled, dont know if its a facing mechanic or just really bad luck on my part.

Got the drop today after kill 163. Did two attempts at the big boss to see what it was all about... 64% on the second attempt was the lowest I could manage before logging. Will probably kill it tonight when I log back in.

I just seem to do poor DPS. I should install a meter, really. I mean... I can get him to like, 90% before the first imp phase, less if I'm doing a good run, but as soon as the adds start to spawn, my dps is lost completely. Might just wait until I have better gear

i have the same issue, for the most part i get to the 2 nd felhunter phase every attempt with the oddball ones that i dont make it, i handle it just the same as the first, los pit lord, ROF portal, go to the pillar to the left and havoc one, i may however not be pooling enough embers to kill them fast enough, some how though they still get the enslave dispelled, dont know if its a facing mechanic or just really bad luck on my part.

I stubbornly did it Demo instead of Destro but had the same basic issue you describe and didn't get how they were dispelling the enslave during the 2nd wave when the pit lord was safely tucked away.
Then I realized that they actually weren't dispelling him but it was around that time that the natural 5m timer on the enslave was falling off.
I reminded myself to re-enslave after dealing with the first wave of felhunters and had a pretty smooth kill a couple of attempts later.
That may not be your issue but with all the things you have to think about on this fight thought I would throw it out there for anyone who might be missing the same thing.

Losing your pit lord on the 2nd wave shouldn't wipe you, I lost mine but I was prepared for it since I was already running away from him. Just finish off the hunters as fast as possible and re-enslave, use cooldowns if you have to. Unbound will if he happens to charge, he doesn't really have so much damage that you can't tank him for a few seconds while you finish the felhunters.

If you leave without killing Kanrethad, you will be brought back to the final phase. It saves your progress.

---------- Post added 2013-03-15 at 04:23 PM ----------

Originally Posted by markw4250

I [...] had the same basic issue you describe and didn't get how they were dispelling the enslave during the 2nd wave when the pit lord was safely tucked away.
Then I realized that they actually weren't dispelling him but it was around that time that the natural 5m timer on the enslave was falling off.
I reminded myself to re-enslave after dealing with the first wave of felhunters and had a pretty smooth kill a couple of attempts later.

I've been banging my head against the 2nd wave of fel hunters for a couple hours worth of attempts. thank you for the reminder!

expected more with regards to the difficulty. The only thing that caused me concern was when at the end there was 1 doomguard to fear, 1 to banish, then the pit lord to re-enslave, all the while hoping that Glyph of HS would bring my health high enough for the Sacrificial Pact to shield me from his Chaos Bolt. Took 11 tries. 513 item level, killed 12 seconds before Curse of Ultimate Doom expired so I guess I really took the safe way out of it.

Enjoying the challenge

I main a pally, and have for over 8 years. I have 11 different character alts, all above 85.

During Cataclysm, my warlock was the last to hit 85, and even after I did I really disliked the class, found it to have way too many options and buttons and it was just a mess, for me, and she was shelved.

My Warlock was the 3rd to hit 90 because I had heard of the green fire quest and wanted to give the class quest a go.

At an ilvl of 483 I acquired the book from Isle of Thunder. I was so excited to be going in to try this quest. I liked to consider myself as a relatively good warlock, able to easily top DPS meters in LFR (which is all I do) as destro. Moving through the scenario I enjoyed running through BT stealthily and talking to Akama again. "This is a piece of cake" I tell myself.

Might I mention I had not looked at any guides, and didn't even look at Wowhead for any information.

I run through the gauntlet with my Eye of Kilrog (which I might say was a great little addition), using raid target markers on the ground so I knew where to run to. I approach the middle of the Reliquary of Souls boss and prepare myself, I knew I had to beat something here, so I got my talents sorted for solo running.

Annihilated. The first boss. My cocky self has just been taken down a notch. I couldn't even beat the little adds that spawned. I try again, I still have problems. I'm amazed, I thought I was a great warlock, turns out, I'm only good at one thing, topping the charts. If I'm going to want to do this, I need practise (and maybe a little help from gear).

I attempted the boss until I was red in the armour. I'm now dedicating the 95% of the time I spend on an alt, to my warlock. I must get better, there is so much I need to learn.

I have to thank Blizzard for such an amazing quest line/solo scenario, just when I thought the difficulty of the game was diminishing, I have a new goal.

I can only hope a Pally class quest were to be introduced to be as difficult as this one

"This is my story,
It'll go the way I want,
Or I'll end it here!" - Tidus (FFX)

Also you shouldn't really need much more in the way of gear, I've seen people saying they've done it with gear as low as yours (I think one person said something in the 470s range). What spec are you doing it as?

I've gone through roughly 6 flasks, and I'm stuck at the felhunter second wave. I just can't seem to manage the pit lord dropping enslave, banished doom lord and 3 pups at the same time, the felhunters eat through my shields and I get wafflestomped by the chaos bolt.